Well, the article has some false information. It says that the network is currently able to process 7 TPS, and would be able to process 27 TPS with a 4 MB block size limit. This is false. Realistically we are looking at a TPS of around 3 right now, so with a 4 MB block size limit we would look at ~12 TPS. I'm actually wondering how people aren't aware of this and don't understand that Bitcoin can never come close to Visa (if we focus on scaling via the block size limit).
Let's say that 700 million people use Bitcoin (that's ~10% of the World population), and that they all make only 1 transaction per day. Transaction size is averaging half a kilobyte today (source Bitcoin Wiki).
700 million transactions * 0.5 = 350 million Kilobyte = ~350 GB/ 144 (blocks per day) = ~2.4 Gigabyte per block. This is only if they make a single transaction per day (which is unlikely, as the average would be much higher with adoption on this scale).
Even with the 7 TPS for 1MB block, there is not much improvement for the 2MB block. For the speed to be really high, we need centralised processor.
the only correct thing that lauda said is that bitcoins 1mb is 3.3tx/s max.. (as the average is 2000 transactions per 600 second block)
but the failure of many people is that they think visa is just one network/one ledger..
so lets take these 2 websites.
http://www.statista.com/statistics/279275/average-credit-card-transaction-volume-per-card-worldwide/in 2012 the average number of transactions per visa card holder was 40 transactions a year
this is due to some users only using it 2 times a year or once a month and some users using it daily.
now if we apply that average to the 104million US visa card holders, then that is an average of 4.160billion transactions a year
http://budgeting.thenest.com/percentage-americans-credit-cards-30856.htmlwhich if we take 2mb+segwit (8000tx per ten minutes) is 420million transactions a year.
so bitcoin with 2mb+segwit can handle 10% of visa americas ledger.
meaning if bitcoin blocks were 20mb in lets say 10-15 years. bitcoin can easily handle 4.2billion transactions and it wont take 60 years, like visa took. it would take only 10-15 years for bitcoin (based on technology growth)
so one ledger of visa can handle 10x more then one cryptocurrency ledger
as for other countries. well they are separate visa ledgers, so you might as well compare Visa UK to blockchain sidechain A and visa Europe to blockchain side chain B, etc, etc.
then you would have a fairer comparison of network ledger settlement vs network ledger settlement
in short
try not to think of combining visa's MULTIPLE ledgers when comparing it to bitcoins single ledger. as thats just a fools attempt of trying to coax people away from bitcoin to a pump'n'dump alt like ether, monero, etc.
think about bitcoin not for todays abilities compared to visa worldwide. but based on bitcoins 15 year growth potential where XXmb+segwit+sidechains would the comparable of visa 60year old network
remember bitcoin has 2million users. visa has 100million(us) 800million(world) users. so bitcoin does not need to surpass visa today, but does have the potential over the next 15 years.